▎ 摘　　要

The present work deals with the microstructure and mechanical characterization of the Al6061 based nanocomposites (2 wt% Graphene and 2 wt% Al2O3) and hybrid nanocomposites (2 wt% Al2O3 with 0.5, 1, 1.5, 2 and 2.5 wt% of Graphene) processed through ultrasonic-assisted melt-stirring technique. The combined effort of reinforcement processing (ball-milling) and ultrasonic-assisted melt stirring approach has been adopted for fabricating hybrid nanocomposites with uniformly dispersed ceramic nanoparticles and carbon nanomaterial. The grain structure, physical properties, fractured surfaces, microhardness, hardness, ultimate tensile strength (UTS), flexural and compressive strength of the Al6061, Al6061-based nanocomposites and hybrid nanocomposites were examined to understand the influence of ceramic and nanomaterial particles on the microstructure and mechanical characteristics of the fabricated specimens. Microstructure investigation employing optical microscopy (OM) images and scanning electron microscopy (SEM) revealed homogenous dispersal of nano-sized Al2O3 and Graphene particles in the prepared hybrid nanocomposite specimens. The mechanical properties of the hybrid nanocomposites enhance with the increase of graphene nanoparticles (up to 1 wt%) in the nanocomposite. The mechanical characteristics of the hybrid nanocomposites exhibited a decreasing trend with an increase in Graphene up to 2 wt%, and an increasing trend is observed with a further increase in Graphene after 2.5 wt%. Al6061-2 wt% Al2O3-1 wt% Graphene hybrid nanocomposite depicts enhancement in compressive strength, UTS, flexural strength, hardness and microhardness of about 105.55%, 171.70%, 37.86%, 71.11% and 34.78%, respectively as compared to carted Al6061 specimen.